Ford had the best 4X4 chassis until they started that silly front axle design that was split in the middle in the late 70's.
then Chevy had the best 4X4 setup until they decided to go with IFS with the '88 redesign.
i think Dodge still has good old solid axles under the front of their 3/4 ton and larger trucks- probably even indestructible Dana 60's.
regarding the frames- the frame on my 81 Ford F250 had a bunch of holes stamped in the frame rails from behind the cab all the way to the back bumper mounts and the frame rails were only 1/8" thick. i don't know what the logic was for that in a 3/4 ton truck that had all the other HD 3/4 ton parts, but that had to make the truck a lot weaker.. as a contrast, the '80 3/4 ton frame under my '87 GMC body is solid all the way back to the bumper and probably 3/16" thick at the thinnest point. it's pretty damn beefy sompared to my old Ford. according to the scales at the yard where i haul scrap iron from time to time, my trusty GMC is about 350 pounds heavier empty than the Ford was.